Hello Lindsay,
if you want to emulate slower links you can use QoS tool shaping
example
controller t1 3/2
framing esf
linecode b8zs
channel-group 0 timeslots 1-23
policy-map shape-all-500k
class-map default
shape average 500000
int ser3/2:0
!
service-policy shape-all-500k out
do it on both ends and you can test applications.
One side has to provide clock to the other one in back to back so one controller needs
clock source internal
Hope to help
Giuseppe